This document claims priority and contains subject matter related to Japanese Patent Application No. 2000-365659 filed in the Japanese Patent Office on Nov. 30, 2000, and Japanese Patent Application No. 2001-352045 filed in the Japanese Patent Office on Nov. 16, 2001, and the entire contents of each of which are hereby incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to an electrophotographic image forming apparatus, such as, a copying machine, a printer, a facsimile machine, and other similar devices having a powder classifying device. More particularly, the invention relates to a powder classifying device that classifies powder for reuse.
2. Discussion of the Background
An image forming apparatus, such as, a copying machine, a printer, and a facsimile machine, employs an electrophotographic image forming process. In this type of an image forming apparatus, an electrostatic latent image formed on an image bearing member (e.g., a photoreceptor drum) is developed with powder such as toner (hereinafter called toner as a representative example of powder) to form a visible image (e.g., a toner image). A toner image formed on the image bearing member is transferred to a transfer sheet by a transfer device. Subsequently, the transfer sheet having the toner image is conveyed to a fixing device, and the toner image is fixed onto the transfer sheet under the influence of heat and pressure by the fixing device.
Generally, residual toner that is not transferred to the transfer sheet and remains on the surface of the image bearing member is removed by a cleaning device such as a cleaning blade, and is then collected to a used-toner collecting container for disposal.
Recently, from the viewpoint of environmental protection, there is an increasing demand for effective use of resources. In addition, a cost reduction is desired such as extending the useful lifetime of toner. For these reasons, reuse of the collected toner has been demanded. In order to fulfill these demands, the above-described image forming apparatus employing an electrophotographic image forming process has employed a device that collects residual toner on the image bearing member and returns the collected toner to a developing device and a toner replenishing device for recycling.
When toner is recycled in the above-described image forming apparatus, a paper powder (paper dust) and aggregated small toner having a relatively large particle size may be included in collected toner. When the collected toner is returned to a developing device and a toner replenishing device for reuse in subsequent development, deterioration of image quality, such as, a white spot and a black spot, may be caused due to the paper powder and the aggregated small toner included in the collected toner.
In order to remove the above-described paper powder and aggregated small toner from the collected toner, a background image forming apparatus employs a filter device. However, a filter of the filter device typically tends to be clogged with collected toner.
According to one aspect of the present invention, a powder classifying device that classifies powder includes a mesh member having meshes, and a brush roller formed with hair-like members and configured to rotate in sliding contact with the mesh member at a predetermined portion in a circumferential direction of the brush roller to push the powder conveyed in a radial direction of the brush roller against the meshes so that the powder is classified into powder passing through the meshes and powder not passing through the meshes.
According to another aspect of the present invention, an image forming apparatus includes an image bearing member configured to bear a latent image, a developing device configured to develop the latent image with powder so as to form a visual image, and a cleaning device configured to remove the powder remaining on the image bearing member. The image forming apparatus further includes a powder classifying device configured to classify the powder removed from the image bearing member by the cleaning device, including a mesh member having meshes, and a brush roller formed with hair-like members and configured to rotate in sliding contact with the mesh member at a predetermined portion in a circumferential direction of the brush roller to push the powder conveyed in a radial direction of the brush roller against the meshes so that the powder is classified into powder passing through the meshes and powder not passing through the meshes. The image forming apparatus further includes a powder conveying device configured to convey the powder passed through the meshes so as to mix with new powder.
Objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.